Canvas HTML5 Top View -> Isometric

We are working in a simple MP strategy game using Node, Express and Sockets! I'm wondering if there's an easy approach to a transformation to make a Top View game into a 3D Isometric, without adding a Z axis to all positions in the game.

Ideally by just updating all the graphic files and the contents on drawing.js which is the controller in charge of doing all graphical operations.